Method and system for distributing energy

ABSTRACT

A method of delivering electrical energy to a point in an electrical power grid, including accessing a source of energy at a first location and converting the energy into a form of transportable energy. The next step is transporting the transportable energy via a bulk transportation network from the first location to the point on said electrical power grid at a second location having a need for additional electrical power without the transportable energy going through the electrical power grid to get to the point. The next step is converting the form of transportable energy into electrical energy suitable for connecting to the power grid and discharging the electrical energy into the power grid at the second location. A system for delivering electrical energy is also provided. The transportable energy preferably takes the form of charged electrolytes, compressed air or thermal storage units, transported, for example, by way of trains.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of Utility application Ser. No.12/274,878, filed on Nov. 20, 2008, which claims priority to CanadianApplication 2,611,424, filed on Nov. 21, 2007, the entire contents whichis incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not applicable.

FIELD OF THE INVENTION

This invention relates generally to the field of energy distribution andmore particularly to the field of distribution of electrical energy inan energy distribution network or power grid.

BACKGROUND OF THE INVENTION

Electricity is currently distributed through a wholesale electricaltransmission network or power grid. Typically, the network is operatedat a higher voltage than the standard voltage for retail consumption.Electricity may be generated at various locations on the grid by varioustypes of power sources, including nuclear generators, coal-fired and gasdriven generators, and hydro electric generators, from where it flowsacross the grid to centres of demand which include retail distributionoperations of for example, local utilities that transmit the electricityonto retail customers, utility operations that distribute electricity toindustrial or large commercial customers, or to such large industrial orlarge commercial customers directly. The form of electrical power thatis transmitted over the long distance portions of the grid isalternating current (AC) at high voltage and it is stepped down toprogressively lower voltages as it approaches a portion of the gridwhere it is to be consumed by the end user. An alternative form ofcurrent is high voltage direct current (HVDC) which must be invertedback to AC before distribution to the end user. The electricity isdirected over a series of electrical wires, supported by power pylonsand hydro poles and is often collectively referred to as the power grid.Significant line losses are a feature of such systems.

The development of the grid is often organic in nature. When powersupply, power demand and transmission capacity grow at different ratesin different locations the potential arises for an excess of supply ordemand with an insufficient transmission capacity to move theelectricity from one location to another. Changing populationdemographics and industry locations exacerbate this problem over thelong term. Local grid expansion due to local utility planning, andregional grid control, in the form of regional independent systemoperators also contributes to a lack of a coordinated overall design.The change in the location of consumption and in the location of powergeneration can result in congestion in the grid at certain points, whichcan prevent a load centre from receiving enough power. Typically, inNorth America, this congestion is regional since the wholesale grid iscomprised of a relatively small number of large transmission lines. Thusa bottleneck at one location results in supply issues for much of thearea on the demand side of the bottleneck (i.e. a big city) that isunable to readily access power from another main transmission line beingtoo remote therefrom. One means currently used for resolving congestionis to allow the market to place a price on the power traversing in thecongested region on the grid. During periods of greater demand, a higherprice can be obtained for the sale of the power through that bottleneck.The higher price can provide the signal for a degree of demandcurtailment.

Electrical demand fluctuates during the day with peaks most oftenoccurring from 8:00 to 10:00 AM and from 5:00 to 8:00 PM. On the otherhand, certain types of low cost power generation are more efficient whenoperated on a continuous basis and other more expensive forms of powergeneration can be operated in response to peaks and demand. The low costtypes of power generation have historically been less attractive tolocate sites near population centres (which are typically also demandcentres) due to transportation costs associated with the fuel used togenerate the electricity, concerns about pollution, and fear of locatingnuclear plants near population centres. In the absence of congestion atspecific bottlenecks, prices near to low cost generation and a distantload centre are similar but with congestion, and a local excess ofdemand over supply, price differences can expand significantly. As aresult, electricity prices are both time dependent and locationdependent in the current power grid. Construction of additionaltransmission capacity is often not an easy, cost effective or adequatesolution to reducing congestion because of the uncertainties of futuredemand. If new routes are required, then it can be very difficult andexpensive to secure the necessary land rights to establish an easementto run the power lines.

Different sections of the grid may be operated by different entitiescalled Independent System Operators. This exacerbates the problems ofmaintaining an overall grid design as the grid tends to be designed in apiecemeal fashion. The grid operators use several means to control thequantity, quality and stability of the power being transmitted so thatthe supply is reliable for the customer. The quantity of powertransmitted is managed by a system of scheduling and coordinating powertransactions between suppliers and consumers which includes managingcongestion and/or providing a marketplace whereby rights to traverse acongested part of the grid are exchanged. The quality of power is alsoin part managed by having generators provide reserves of generation thatcan be called into service at short notice. The quality of power, inparticular the frequency of AC current on the grid, is managed by havingsuppliers provide spinning reserves that can be called uponinstantaneously to help adjust the frequency of the power on the grid orto replace off frequency power supplies. Finally, grid operators alsomanage the voltage of the AC current on the grid through the provisionof voltage support by suppliers to the electrical grid.

Included among these power management strategies are for example, theknown technique of peak shaving. In peak shaving, adjacent to acongested location, electricity may be drawn off the grid and locallystored during a low demand period, and then released from that locationduring a high demand period. Excess demand which is unable to be met dueto the congestion at the transmission bottleneck can be met with a boostof locally stored power. While providing an interim or temporarysolution, this approach of time shifting does not adequately address thefull dynamic nature of the need to match demand to supply through thecongested infrastructure of the power grid. As demand grows, the problemof congestion becomes ever more of a concern, a constraint on efficientdistribution of electrical power, and inevitably a higher cost to theend user.

As well, as newer renewable resources of energy are tapped, they may belocated in sites which are remote from conventional power grids. Indeed,for wind farms and the like, being remote is often preferred.

Efforts exist in the prior art to resolve power grid issues. Forexample, U.S. Pat. No. 5,610,802 describes an energy storage systemwhich is in a housing having a number of doors and internal racks.Battery modules are placed on the racks and the storage system has anenergy storage capacity of 100 kw, and a footprint of less than 400square feet. This patent describes how the energy storage system istransportable and can be deployed to specific locations to deliver apower boost to a system that is stressed, for example, by extreme coldweather.

However, referring to column 15, line 55 this patent teaches that thebatteries be removed and transported separately from the housing duringtransportation, to reduce the shipping weight of the storage system. Itis also contemplated that the batteries be shipped dry, and that theelectrolytes be shipped later. So, this patent teaches moving thehousing, moving the battery cases separately from the housing and thenmoving the electrolytes separately from the rest. In other words theinvention can be moved from place to place, but is intended to becharged from and discharged at the same location. As such it cannot dealwith bottlenecks in the electrical grid.

U.S. Pat. No. 6,026,349 is interesting because it teaches ways toconvert and store energy other than through electricity (i.e. compressedgas). However, in this invention teaches locating the storage/dischargefacility at the margins of two adjacent power grids, so the energy canbe removed from or added to either adjacent grid. The purpose of thisinvention is to permit specific power conditioning, suitable for eitherone or the other grid to be performed, to permit the stored power to bereleased to the power matched grid. However this stationary storageplant cannot be used to for example overcome local bottlenecks in eitherof the adjacent power distribution grids.

U.S. Pat. No. 6,900,556 is also interesting in teaching the use ofcapacitors to temporarily store electrical energy. In this patent theyteach using a large-scale, capacitor-based electrical energy storage anddistribution system capable of effectuating load-leveling during periodsof peak demand on a utility, and of effectuating a cost savingsassociated with the purchase of electrical energy. In a stationary orfixed plant location (for a matter of days or weeks) embodiment acapacitor or multitude of capacitors may be charged with electricalenergy produced by the utility, such as during periods of low demand orlow cost, and discharged during periods of high electrical energyconsumption or high electrical energy cost. One or more capacitors maybe located at a consumer's residence or business. Alternatively, a farmof capacitors may be provided at or near a utility, or at or near alocation experiencing high demand.

In another embodiment, one or more capacitors may be located in or on avehicle, such as an automobile, a truck, or a train of a light railsystem.

In this embodiment the patent teaches using the stored energy on thevehicle, to drive the vehicle from place to place, for example to permita light rail line which does not need a power transmission line alongits length, therefore reducing the capital cost of the transportationsystem, (see column 11, lines 5 to 8). In some cases the electricalenergy can be applied to a load in the source, but applying the energyto a load does not overcome bottle necks in electrical distributionnetworks, by making more electricity available on the other side of abottleneck, which would require power conditioning means to make theelectrical energy suitable for adding to the grid at that point.Furthermore, by consuming electrical energy to drive the vehicle, therewill be little left over to provide at the load.

Other prior art patents of general interest in power storage and energydistribution include U.S. Pat. Nos. 3,682,704; 5,439,757; 5,798,633;6,475,661; 6,649,289; 6,653,749; 7,199,550; and U.S. Publication No.2004/0197649.

What is desired is a form of resolving problems of getting electricityfrom a location where it can be generated at a low cost, and deliveringthe electricity beyond the congestion bottlenecks or infrastructure gapsto where it can be sold for a high price. What is required is a way ofproviding such electricity which is dynamic and can be adapted forchanges in the demand location over time without requiring expensivecapital improvements to the existing grid, without requiring newexpensive right of ways, and without exposing people to more incidentelectro-magnetic fields associated with high tension electrical wires.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a method ofdistributing electrical energy to a point in an electrical grid withoutthe electricity going through the electrical power grid to get to thepoint. The present invention also comprehends a distribution system forachieving such power distribution.

Therefore according to a first aspect the present invention provides amethod of delivering electrical energy to a point in an electrical powergrid, said method comprising the steps of:

accessing a source of energy at a first location;

converting said energy into a form of transportable energy;

preserving and transporting said transportable energy from said firstlocation having said source of energy to said point on said electricalpower grid at a second location having a need for additional electricalpower without said transportable energy going through said electricalpower grid to said point;

converting said form of transportable energy into electrical energysuitable for said electrical power grid at said point and

discharging said electrical energy into said power grid at said point.

According to a further aspect the present invention provides a method ofdistributing electrical energy to a point in an electrical grid withoutsaid electricity going through said electrical grid to said point, asstated above wherein said step of converting said energy into a form oftransportable energy comprises changing an electrochemical potential ofboth a positive and a negative liquid electrolyte at a charging stationconnected to said source of electrical energy;

said step of transporting said transportable energy comprisestransporting said liquid electrolytes from said first location to saidsecond location and said step of converting said form of transportableelectrical energy comprises placing said liquid electrolytes in adischarging station at said point in said electrical grid at said secondlocation; and

discharging electricity to said point through said discharging station.

According to a further aspect the present invention provides adistribution system for distributing electricity around, but notthrough, a power grid said distribution system comprising:

a first compressor connected to a source of power at a first location tostore energy by compressing air into a compressed air storage container;and

a means for preserving and transporting said stored energy in saidcompressed air storage container to and from said first locationcompressor;

a second means for converting compressed air into electrical energy,said second means being connected to said electrical power grid at asecond location for receiving said compressed air from said; compressedair storage container

wherein said second means conditions said electrical energy to becompatible with said power grid at said second location and distributionsystem permits electrical power to be added to a point in the power gridwithout being transmitted through said grid to said point.

According to a further aspect the present invention provides adistribution system for distributing electricity around, but notthrough, an electrical power grid, said distribution system comprising:

a charging station connected to a source of power at a first location toconvert electrical energy into a form of transportable energy;

a means for transporting said transportable energy from said firstlocation to a second location;

a discharging station at said second location connected to saidelectrical power grid to convert said transportable energy back intoelectrical energy; and

an electrical connection between said electrical power grid and saiddischarging station to permit said electrical energy to be dischargedinto said electrical power grid at said second location.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made, by way of example only, to preferredembodiments of the invention, in which:

FIG. 1 is a schematic of a power grid;

FIG. 2 is a price vs. time plot for two points, A and B in the powergrid of FIG. 1;

FIG. 3 is a plot of the price difference between the points A and B ofFIG. 2;

FIG. 4 is a schematic of a charging and a discharge arrangementaccording to one embodiment of the present invention;

FIG. 5 is a transportable container according to one aspect of thepresent invention;

FIG. 6 is a transportable container according to a second aspect of thepresent invention;

FIG. 7 is a transportable container according to a further aspect of thepresent invention;

FIG. 8 a is a view of a network arrangement according to the presentinvention;

FIG. 8 b is a pricing table for wholesale electrical energy fordifferent times and places in the transportation network of FIG. 8 a;

FIG. 9 is a transportable storage container for a thermal storage fluidaccording to a further aspect of the present invention;

FIG. 10 is a transportable storage container for a phase change thermalstorage material according to a further aspect of the present invention;

FIG. 11 is a transportable storage container for layers or plates ofsuper capacitor energy storage media according to a further aspect ofthe present invention;

FIG. 12 a is an example of one format of transportable energy conversionequipment according to the present invention;

FIG. 12 b is an example of a second form of transportable energyconversion equipment according to the present invention; and

FIG. 12 c is an example of a third form of transportable energyconversion equipment according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a schematic of a portion of a power grid system. At theleft hand side a source of power 10, which might be any conventionalsource of power such as a coal or gas fired power plant, nuclear plant,wind farm, hydro electric dam of the like. Adjacent to the source ofpower 10 and located on the power line 12 is a grid point A. The powerline 12 extends typically a significant distance across a series ofpower grid sections (not shown) eventually, the power line 12 ends upadjacent to a high load or heavy demand district 14. This is illustratedby a plurality of branches 16 which extend from the power line 12 withinthe area 14. Also shown is a second grid point B adjacent to the highdemand area 14. Also shown is a dashed line 11, which is explained inmore detail below.

Electricity produced at the source of power 10 passes through grid pointA on the power line 12. Eventually the power reaches grid point Badjacent to the demand area 14 still on the power line 12. As can beappreciated, the demand for electricity at point B adjacent to thedemand area 14 will be significant. In the event that the demand in area14 grows in size beyond that which can be easily transmitted to point B,for example by reason of a capacity limit or constraint on the powerline 12 at point C, there may be a shortage of supply of electricitywhich can pass through point C to meet the demand in area 14 past pointB. In this circumstance, the price of power will rise and a certainrationing of power consumption will occur in the area 14 by reason ofthe higher price.

In contrast, at power grid point A, there is little local demand meaningthat the power being transported along the line 12 is generally alwayssufficient to meet the small amount of change of local demand. Thus, theprice fluctuations for power over a 24 hour period at point A are muchless than those experienced at point B because power demand is not inexcess of the power carrying capacity of the grid at that point.

FIG. 2 shows a graph in which the price of the electricity charged tocustomers at point B, past the line capacity constraint at point C, isshown with Line B and the price to customers at point A is shown at LineA over a typical 24 hour period. The absolute values will of coursefluctuate over time, from year to year and the like. What is relevant tothis invention is the cost pattern, rather than the specific costamounts. As can be seen from the power price curve, two price peaksoccur in the cost of the electrical power, one in the morning betweenapproximately 6:30 AM and 11:30 AM and a second one occurs beginning atapproximately 2:30 PM and the costs rise until a peak is reached ataround 6:30 PM. Then, power cost declines over time until it reaches aminimum around 10:30 PM. This pattern is true for both grid points A andB. It will now be understood that even though the grid point A islocated somewhat closer or adjacent to the source of power 10, therewill still be a price change with time during each day with peaks 22 and24 which are generally at or about the same time as the peaks 16 and 18for the power at grid point B. There is a difference however in terms ofthe relative cost with the prices at grid point B being significantlyhigher due to the larger local demand and the bottleneck effect at pointC of the transmission capacity limits of power line 12.

FIG. 3 plots the price difference between the power costs versus timegraphs of FIG. 2. As can be seen, the relative costs vary significantlybetween grid point A and grid point B over the typical 24 hour cycle. Itwill be understood by those skilled in the art that the power costcurves shown are illustrative in nature, and are not intended to reflectthe exact amounts of any specific location. However, the trends shown bythe graphs are believed to be generally representative of what occurs.

An aspect of the present invention is to take advantage of the pricedifferential between grid point A and grid point B at different pointsof the daily price cycle. The present invention in one embodimentinvolves the delivery of electrical energy, for example to grid point B,from electrical energy extracted from at or about grid point A whichelectrical energy is not delivered by means of power line 12. Thus, thepresent invention comprehends delivering electrical power from gridpoint A to grid point B without transmitting the power along the powergrid or electrical power line 12. The advantage of the present inventionis therefore to avoid the transmission bottleneck of the power gridlocated before point B at point C. Thus, in addition to the timeshifting of power delivery of the peak shaving method of the prior artthe present invention adds location shifting.

As shown in FIG. 1, the dashed line 11 illustrates the alternate routefor the energy according to the present invention. In some cases, thesource of power 10 does not generate electricity so the dashed line 11represents getting the power from the power plant to the point A. Fromthere the energy, in the form of a transportable energy that can bereadily converted into electrical energy, is transported along route 11,to point B.

According to the present invention, there are a number of most preferredways of so delivering power along route 11. While these two mostpreferred ways are discussed in detail below, it will be understood bythose skilled in the art that other ways of implementing the presentinvention are also comprehended. In the first preferred embodiment ofthe present invention, a charging device is used to change theelectro-chemical potential of a positive and negative electrolytesolution at the location of grid point A. In other words, abundant andrelatively low-cost power is used to change the electro-chemicalpotential of the electrolytes in a manner analogous to a flow battery.

FIG. 4 shows the elements of a charging station 50 according to thepresent invention. According to the present invention, a specific andcost effective type of electrolyte charging and discharging arrangementcan be used to transport electrical energy from point A to point B inthe grid without necessarily going through the grid points namely, alongroute 11. More specifically, an electrolyte charging station illustratedat 50 in FIG. 4 can be provided at grid point A, where the cost of poweris low. In addition to being a lower cost source of power, charging canbe time modulated to ensure that the lowest price of power at grid pointA is used. The electrolyte charging station 50 consists of a source ofgrid power 52 which feeds into a power conversion system and high speedgrid connection controller 54. A rectifier 56 is provided to convert thepower from AC to DC.

Like a flow battery, the charging station 50 of the present inventiondiffers from a conventional battery in that the chemical reaction occursbetween two electrolytes rather than between an electrolyte and anelectrode, and the electrolytes are stored external to the electrodesection and are only circulated through the electro-chemical cell stackas required to store electrical energy. As in a flow battery thecharging station 50 uses an electrode that does not take part in theelectrochemical reactions, but merely serves as a substrate or aconductor.

The positive 58 and negative 60 electrolyte are circulated through thecell stack 62 where the DC current is applied across the electrodes 64,66 (not shown) to create an electro-chemical potential between the twoelectrolytes. Ions pass across the membrane 68 to change theelectrochemical potential of the electrolytes. Banks of cells may belinked together to create a bipolar module cell stack where theelectrodes are shared between adjacent cells with the cathode of thefirst cell becoming the anode of the next cell and so on. Linked inseries, sufficient cells in the stack can then form the desired voltagefor the cell stack. During operation, the circulation control systemcauses the electrolytes to flow from two separate storage tanks throughthe cell stacks. A negatively charged electrolyte 60 and a positivelycharged electrolyte 58 are used on opposite sides of the membrane. Theelectrolytes flow to the cell stack where ions are transferred betweenthe two electrolytes across the ion exchange membrane 68. After thereaction, the electrolytes are returned to separate storage tanks 70,72. Most preferable these electrolytes are placed into transportablestorage containers 70, 72, for example, railway tankers, fortransportation to a second location, such as point B. The amount ofelectricity transported, is directly related to the volume ofelectrolyte that is being transported and the energy density of theelectrolyte used.

As will be understood by those skilled in the art, there are a number ofspecific chemistries for the electrolytes, including, vanadium redux,zinc bromine, polysulphide bromine, and cerium/zinc. One advantage of anelectrolyte charging system as described is that the electrical storagecapacity is related only to the liquid storage capacity of theelectrolyte storage reservoirs. The present invention takes advantage ofthe external storage aspect of the electrolyte.

Located beyond the transmission bottleneck, at point C, is point B,which has an electrolyte discharging apparatus 100, which is thegeographically remote second part of a first embodiment of the presentinvention. It also has a cell stack 102, which may be characterized as adischarging cell stack 102 (the right side of FIG. 4). Most preferablythe charging and discharging locations are each located adjacent to aconvenient transportation corridor, such as a railway line, so that atrain, for example, can be used to haul the liquid electrolytes betweenpoint A and point B, even though point A and B are geographically remotefrom one another. At point B, the electrolytes 58, 60 can be passedthrough the discharging cell stack 102 by a circulation control systemso as to pass ions across the membrane 104 and cause an electricalpotential to arise between the electrodes 106, 108 (not shown). Aninverter 110 (DC to AC) inverts the electrical power, and through apower conversion system 112 and high speed electrical grid connectioncontroller the electrical energy is dumped back into the grid. It willbe appreciated that after the electrolytes 58, 60 are circulated pastthe membrane 104, they can be reloaded into the transportable containers116, 118 for delivery back to grid point A for recharging. Theelectricity is therefore provided or made available beyond thetransmission bottleneck C. This electricity can be sold at a higher rateat point B than it was purchased for at point A and can be used toalleviate supply issues arising beyond the bottleneck at C. As can nowbe understood the time of discharge can be controlled to optimizerevenue, and the type of discharge can be controlled to achieve powerconditioning ends such as voltage support, frequency control and/orspinning reserves.

The present invention comprehends that the facilities to extractelectricity at point A, then to add electricity at point B, be made withas little cost as possible. Therefore, rather than building a completeflow battery at each location A and B, the present invention comprehendsbuilding an electrolyte charging station 50 at the low cost power siteA, and an electrolyte discharging station 100 at the higher pricedlocation B. Thus, while each location would require a circulationcontrol system for the liquid electrolytes 58, 60 and a cell stack,there would be no need for each location to have both a power inverterand a rectifier, which would always be found in a flow battery.According to the present invention, only charging or discharging isneeded at each location. This reduces the cost of the installations ateach location and the capital cost of implementing the presentinvention.

It can now be appreciated that this embodiment of the present inventionprovides a system for transporting electricity from an oversupplylocation A to an excess demand location B without transmitting theelectricity across the transmission constrained electrical grid throughan infrastructure bottleneck C. It will also be appreciated that theelectrical power delivered can be used for other purposes, such as powerconditioning and the like as may be required to keep the grid in stableoperational condition.

FIG. 5 shows a schematic of transportable storage containers 70, 72,116, 188, which in this case are shown as railway cars 200, transportingthe charged and discharged positive and negative liquid electrolytes 58,60. Although they are depicted as railway cars 200, the presentinvention comprehends that other forms of freight transportation couldalso be used, such as barges, ships or the like.

According to a second embodiment of the present invention, the energycan also be stored by means of a compressed gas storage system. In thisembodiment, the energy is converted, by such means as a compressor orotherwise, into a compressed gas, and again stored in a pressure vesselform of transportable storage container such as a railway car shown as210 in FIG. 6. The railway car 210 can be transported along atransportation route, within a transportation network such as a railwayline, to location B, where the energy can be reconverted to electricalenergy by releasing the pressure of the gas through a generator. Varioustechniques are available to ensure that the energy stored is reliablyrecovered, including, using a heat sink to improve the energy conversionfrom the gas to electrical energy. An example of such a conversion is asfollows.

Compressed air energy storage (“CAES”) carries out said conversion bysending stored compressed air, mixed with a fuel source for heatgeneration, into a combustion chamber. The hot, expanding exhaust gasesdrive turbine blades in a turbine connected to the output shaft of thedevice that in turn drives the input shaft of an alternator.

Thermal and compressed air storage (“TACAS”) carries out said conversionby sending stored compressed air through a pre-heated thermal storageunit and, in its simplest form, into an expansion turbine that drivesthe input shaft of an alternator. Use of TACAS technology accommodatesthat the sources of energy be used to be in the form of transportableenergy, e.g., stored heat and stored compressed air. The presentinvention comprehends various configurations, such as simple or morecomplex turbine configurations in which the heating of the air isprovided by an external heat source, or a combination of external heatsource and stored thermal energy.

CAES and TACAS require a short period of time, typically between one andfive minutes to reach full output. Therefore in order to make the CAESand TACAS conversion of stored energy to electricity applicable to powergrid ancillary services such as voltage support, frequency control andspinning reserves these configurations may include a flywheel or ansupercapacitor either transported with the transportable energy orlocated at the discharge station to permit instantaneous response togrid requirements.

As with the previous embodiment the preferred form of the transportableenergy is one that is as energy dense as possible to make thetransportation costs as low as possible. Thus the present inventioncomprehends configuring the transportable storage containers in a mannerthat maximizes the efficient transportation of the energy.

A “transportation network” according to the present invention means aset of transportation paths, with discrete starting and endinglocations, along which transportation occurs within that network. Therestrictions of a limited set of paths and nodes are offset by higherefficiency of bulk transportation and the ability to use existinginfrastructure. A preferred transportation network according to thepresent invention is a railway network. Such a network can be used tominimize unit transportation costs and yet operate on a large enoughsize to benefit the power grid with network effects, as well as pricedampening and grid stabilization. “Freight transportation” refers to thepreservation and bulk transportation of transportable stored energyaccording to the present invention on a large enough scale for theelectrical energy to be suitable for conditioned connection to thewholesale power grid at, for example, a substation.

FIG. 6 shows an alternate embodiment of the transportable container, at210, which is in the form of a reinforced pressure vessel, to carrycompressed gas as explained below. Again, while a railway car is shown,other forms of transportation vehicles are also comprehended for movingthe pressure vessel from point to point such as barges or the like.

FIG. 7 shows a further embodiment of the transportable container, inwhich a heat sink or thermal storage material 230 is provided in thethermally insulated vessel 220 to retain, upon heating, thermal energy,for increasing the efficiency of the conversion of the pressurized gasinto electricity or for the direct operation of an engine or enginesystem that uses heat as energy source for generating electricity.Passages 240 through the thermal storage material are also shown forheat transfer. Again, any suitable freight transportation can be used,although railway cars are likely preferred as the low costtransportation method.

As can now be understood, in this embodiment, the same principles apply,namely, that the energy can be acquired at a low cost location,converted to a transportable form of energy, and then transported to anygiven location for re-conversion back into electrical energy and forre-sale at that point. The present invention comprehends that there maybe a plurality of discharge locations serviced by one or more charginglocations. The delivery of electrical energy can be coordinated tomaximize economic value of the electricity at the location adjacent tothe load which may be sold as raw power, used as reserve power or usedfor power conditioning purposes and the like.

FIG. 8 a shows how the capability of the present invention may be usedto relieve multiple transmission bottlenecks or to provide spot deliveryof the electrical power to any point where it might be usefully used.For example, a single charging location 300, can be used to supplytransportable energy to a plurality of discharging locations 310, 320,or 333, depending upon the local demands, transmission bottlenecks andpower grid requirements. The charging location 300 can be located withinone independent system operator's grid, and the discharging location canbe located within a second independent operator's grid. In this examplethe present invention comprehends directing the transportable energy tothe location 310, 320 or 330 where the economic value for the electricalenergy can be optimized. Thus the present invention comprehends both amethod of distributing the transportable energy and a distributionsystem consisting of at least one charging location adjacent to a lowcost source of power, or a renewable source of power, or a lowgreenhouse gas producing source of power, for creating a transportableform of energy, a transportation network and at least one discharginglocation located on the demand side of a transmission bottleneck fordischarging said energy.

Another aspect of the present invention is shown in FIG. 8 b where themost suitable selection of location for discharge may change both duringthe period of charging and during transport. Initially at 5:45 am,during charging, the discharging location on the transportation networkthat offered the highest price was location 320, but that was for 6:00am not the anticipated discharge time of 10:00 am. By the time chargingwas completed at 8:00 am the price that could be received for the storedenergy was highest at discharging location 330. However by 8:15 am andafter the transportable energy was already in transit the highest pricefor the transportable energy at the expected discharge time of 10:00 amwas at location 310, so a contract to discharge at that location can bebooked.

The network effect of this invention permitted a higher realised energyprice of $6.60 per megawatt hour than was initially available, e.g. Theseller actually received $95.80 at discharge location 310 rather thanthe $89.20 at discharge location 320 which was originally expected whenstarting to charge. The flexibility of the energy transportation systemof the present invention also enabled a greater price realisation of$5.75/megawatthour than was anticipated when the transportable energyfirst began to move, e.g. the $95.80 actually received at location 310as compared to the price of $90.05 at location 330 which was the highestprice when transportation began. This flexibility arises in oneembodiment, from having multiple charging stations. As can now beappreciated, the more network nodes, whether charging, discharging orboth, the more flexible the supply of conditioned electrical energy fromthe transportable stored energy becomes. Thus an aspect of the presentinvention is to monitor the price of electricity in the power grid, andto direct the transportable energy to locations in the grid as dictatedby those local prices to optimize financial returns. For best effect theprices should be monitored in real time.

Another aspect of the present invention can now be understood. Referringto FIG. 1, the dashed line 11 is shown between the source of power 10and the point A. In cases where no electric transmission infrastructureexists, for example, at a remote wind farm, there may be no need to turnthe power into electricity first. For example, at a wind farm to convertwind energy into electrical energy entails some losses. To turn theelectrical energy into transportable energy will entail further losses.And, upon reconnecting, converting the transportable energy intoelectrical energy involves further losses. In the case of the pressurestorage form of energy of the present invention, the wind energy can beconverted directly into transportable energy (pressurized gas) withoutfirst being transformed into electrical energy to reduce conversionlosses which might otherwise be incurred.

In a further alternative, FIG. 9 of the present invention comprehendsstoring the heat energy in a fluid storage medium such as hot oil ormolten salt. Referring to FIG. 9, a fluid thermal storage medium 470 isplaced into the thermally insulated storage vessel 475 via input pipe435. At the discharge location the fluid thermal storage medium isremoved via outlet pipe 445. Again, any suitable freight transportationcan be used, although railway cars are likely preferred as a low costtransportation method.

In a further alternative, FIG. 10 shows various phase change energystorage materials 480 in the form of, one or a combination of, gases,liquids, solids, plasma or otherwise having a high heat capacity withinan insulated thermal storage container 485 which would also be suitableaccording to the present invention. In this embodiment a piping system450 and 460 would permit the heat to be extracted, typically using aheat transfer fluid, from the storage medium 480 at a discharge locationand the heat would be used to run a Sterling heat engine connected to anelectric generator for example to generate the electricity.

In a further alternative, FIG. 11 shows a supercapacitor composed of, asan example, layers of alternating positive 490 and negative 495electrodes kept apart from each other by electrical insulationdielectric materials or by separating layers, 491. At the chargingstation, direct current voltage is directed into connection 66 and outof connection 64. At the discharging station direct current isdischarged out of connection 108 with the returning circuit completingat connection 106. The amount of electricity transported is directlyrelated to the unit size, and thus unit weight, of the supercapacitorsthat are being transported and their energy density.

As will be understood by those skilled in the art, there are a number ofspecific configurations and compositions of both electrode plates andany separating layers. One advantage of a supercapacitor charging systemas described is that the electrical storage capacity is relatedprimarily to the surface area of the dielectric insulators or separatinglayers, given any particular supercapacitor technology, and thus to theweight of the supercapacitor. The present invention takes advantage ofthe massive bulk carrying capacity of means of freight transportation.This further permits advantageous tradeoff of unit weight for energystorage capacity unit cost, such that heavier but lower capital costsupercapacitors can be used that would not be as practical in other waysof using and deploying supercapacitors.

The concept of this invention of using energy transportation media otherthan the power grid is suitable for relieving power grid bottlenecks aspreviously explained, but is also particularly useful, for example, forwind or solar energy sources that might be too remote to be evenconnected to a grid. In such cases the direct heating of a fluid thermalstorage medium for example is seen as particularly advantageous, as iteliminates the capital cost of running a fixed electrical line to theremote location (i.e. connecting the solar thermal farm to the powergrid) and also eliminates the line losses associated with thetransmission of electrical power, which can also reduce the overallgains available from such renewable energy sources.

Various types of transportation of the energy storage media and bothfixed routing and flexible routing transportation networks arecomprehended by the present invention including barges, moving through amaritime ship transportation network, a canal network, intermodaltransportation, from barge to railcar or the like, and further includinga barge canal network which is interconnected to a railway network withintermodal transportation capabilities. As can now be better understoodan advantage of the present invention is that it utilizes existing bulktransportation infrastructure, which have already been built, totransport power in a novel way. Such power, according to the presentinvention is supplied to the wholesale power grid, by being converted,conditioned and connected to the wholesale high voltage power grid.

A further alternative of the present invention as shown is to transportboth the energy storage media, such as the pressurized gas or the liquidelectrolyte, and the energy conversion equipment, such as a turbinegenerator or an electrolyte conversion system such as a flow batteryconversion cell. As will be appreciated by those skilled in the art thecost of transporting the additional components might be offset by theflexibility of discharging location. While the means for conversion ofthe heat energy to electricity, such as a turbine, might be transportedfrom location to location as well (see FIGS. 12 a, 12 b, and 12 c), thepresent invention comprehends that means for conversion would be mostpreferably installed at the discharge location.

In FIG. 12 a, one embodiment of this invention as shown is to transporta pressure driven turbine in a container on a railcar along withcontainers of pressurized gas such that at the discharge location suchthat gas from outlet pipe 420 in FIG. 6 is connected to inlet piping 421of the turbine 422 causing the shafts of the turbine and the generator,423, to rotate thereby producing electricity. The generator is connectedto the inverter and power conversion system at the discharging stationvia electrical connection 106 and 108 in a similar manner to thearrangement in FIG. 4.

In FIG. 12 b, another embodiment of this invention as shown is totransport a heat engine, such as a Sterling engine, in a container on arailcar along with containers of heated fluid thermal storage media suchthat at the discharge location the fluid, 470, from the thermal storagecontainer [475] outlet pipe 445 in FIG. 9 is connected in FIG. 12 b toinlet piping 446 of the heat engine 447 causing the heat engine tooperate and the shaft of the generator, 448, to rotate thereby producingelectricity. The heated fluid thermal storage media is returned from theengine outlet piping, 436, in FIG. 12 b, to the inlet pipe, 435 in FIG.9, of the thermal storage container 475. The generator, 448 in FIG. 12b, is connected to an inverter and a power conversion system at thedischarging station via electrical connections 106 and 108 in a similarmanner to the arrangement in FIG. 4.

In FIG. 12 c, another embodiment of this invention as shown is totransport a Discharging Conversion Cell for Charged Electrolytes, 102,as also shown in more detailed context in FIG. 4, in a container on arailcar along with container, 70 in FIG. 4, of +ve charged electrolytes58 and container, 72 in FIG. 4, of −ve charged electrolytes 60, suchthat at the discharge location the charged electrolytes from thetransportable containers, 200, in FIG. 5 are passed through theappropriate part of the Discharging Conversion Cell, 102 in FIG. 12 c,thereby producing electricity. This transported Discharging ConversionCell is temporarily connected during discharge to an inverter and apower conversion system at the discharging station via electricalconnections 106 and 108, as also shown in FIG. 4.

While various modifications are discussed above, the scope of theinvention is only restricted by the limitations of the attached claims.Various alternative embodiments have been described, such as usingeither liquid electrolytes and flow battery cell stacks to extract andre-inject electricity into selected locations on the power grid, or, byusing a compressed gas energy storage system for the same purpose. Othermodifications are also comprehended by the attached claims.

What is claimed is:
 1. A method of delivering electrical energy to apoint in an electrical power grid without said electrical energy goingthrough said electrical power grid to said point, said method comprisingthe steps of: accessing a source of energy at a first location;converting energy from said source of energy into compressed air energy,thermal energy, or phase-change energy; storing said compressed airenergy, thermal energy, or phase change energy in a transportablestorage container adapted to substantially preserve said energy;transporting said transportable storage container from said firstlocation to said point on said electrical power grid at a secondlocation having a need for additional electrical energy; providing anenergy conversion means at each said second location; converting saidcompressed air energy, thermal energy, or phase change energy intoelectrical energy suitable for supply to the electrical power grid usingsaid energy conversion means; and discharging said electrical energyinto said electrical power grid at said point.
 2. The method as claimedin claim 1, wherein said step of converting said energy from said sourceof energy into said compressed air energy comprises using a compressorto compress and store air into said transportable storage container;said step of transporting said transportable storage container comprisesmoving said transportable storage container by a transportation means,and said step of converting said compressed air energy comprises usingthe energy released upon decompression and expansion of said compressedair to create electricity at said point at said second location.
 3. Themethod as claimed in claim 1, wherein said step of converting saidenergy from said source of energy into said thermal energy comprisesusing a heater to heat said transportable storage container; said stepof transporting said transportable storage container comprises movingsaid transportable storage container by a transportation means, and saidstep of converting said thermal energy comprises using said storedthermal energy to create electricity at said point at said secondlocation.
 4. The method as claimed in claim 1, wherein said step ofconverting said energy into phase-change energy comprises using a heaterto change a phase of an energy storage material to store energy in aphase-changed material which is then held in said transportable storagecontainer in said phase-changed state, said step of transporting saidtransportable storage container comprises moving said transportablestorage container by a transportation means, and said step of convertingsaid phase-change energy comprises rechanging the phase of the energystorage material to release the energy stored to create electricity atsaid point at said second location.
 5. The method as claimed in claim 1,wherein said method includes the further step of returning saidtransportable storage container to said first location for recharging.6. The method as claimed in claim 1, wherein said transportation stepincludes transporting said compressed air energy, said thermal energy,or said phase-change energy by one or more of railway, barge, and ship.7. The method as claimed in claim 1, wherein said electrical energydischarged at said second location into said electrical power grid isfor one or more of power conditioning, voltage support, frequencycontrol, spinning reserves, and bulk power sales.
 8. The method asclaimed in claim 1, wherein said first location is located in atransmission grid controlled by a first Independent System Operator andsaid second location is located in a transmission grid controlled by asecond Independent System Operator.
 9. The method as claimed in claim 1,wherein there is a plurality of discharging second locations, and saidtransportation step includes transporting said compressed air energy,said thermal energy, or said phase-change energy to one of saiddischarging second locations.
 10. The method as claimed in claim 1,further including a plurality of charging first locations and aplurality of discharging second locations wherein said method furtherincludes the step of routing said compressed air energy, said thermalenergy, or said phase-change energy between said plurality of chargingfirst locations and said plurality of discharging second locations. 11.The method as claimed in claim 1, wherein said source of energy at saidfirst location is one or more renewable sources of energy selected fromthe group consisting of solar power, wind power, hydro power, wavepower, and geothermal power.
 12. A system for delivering electricalenergy to a point in an electrical power grid without said electricalenergy going through said electrical power grid to said point, saiddelivery system comprising: a charging station connected to a source ofenergy at a first location to convert energy from said source of energyinto compressed air energy, thermal energy, or phase-change energy; atransportable storage container for transporting said compressed airenergy, thermal energy, or phase-change energy from said first locationto said point on said electrical power grid at a second location havinga need for additional electrical energy, said transportable storagecontainer being adapted to substantially preserve said energy; adischarging station at said second location, each said dischargingstation having an energy conversion means connected to said electricalpower grid to convert said compressed air energy, thermal energy, orphase-change energy back into electrical energy; and an electricalconnection between said electrical power grid and said energy conversionmeans to permit said electrical energy to be discharged into saidelectrical power grid at said point.
 13. The system as claimed in claim12, wherein said charging station is configured to convert said energyinto said compressed air energy by means of a compressor to compress airinto said transportable storage container; and wherein said dischargingstation comprises a means for receiving said compressed air from saidtransportable storage container and converting energy stored in saidcompressed air into electrical energy suitable for connecting to saidelectrical power grid wherein said electrical energy can be dischargedinto said electrical power grid through said electrical connection. 14.The system as claimed in claim 12, wherein said charging station isconfigured to convert said energy into said thermal energy by means of athermal generator to store thermal energy in said transportable storagecontainer; and wherein said discharging station comprises a means forreceiving said thermal energy from said transportable storage containerand converting said thermal energy into electrical energy suitable forconnecting to said electrical power grid through said electricalconnection.
 15. The system as claimed in claim 12, wherein said chargingstation is configured to convert said energy into said phase-changeenergy by means of changing the phase of a phase-change energy storagematerial to an energy retention phase which is then stored in saidtransportable storage container; and wherein said discharging stationcomprises a means for receiving said phase-change stored energy fromsaid transportable storage container and converting said phase-changestored energy into electrical energy suitable for connecting to saidelectrical power grid through said electrical connection.